It's no surprise that a Nelson Muntz-style beating will land kids in the nurse's office, but according to a new study, both bullies and their victims are more likely to see the nurse, and not just for bruises and scrapes.

Researchers from the University of Kansas in Lawrence followed a group of 600 students in grades 3 though 5 for a year. The children answered questionnaires about how often the were targeted, and who the bullies were in their class. Later they matched up this information to logs of how often each child visited the nurse.

Most kids wound up in the nurse's office four or five times a year, but the number was higher for bullied kids and those identified as aggressors. Sometimes these children were sick or injured, but often they had more vague complaints, like a stomach ache.

The researchers say this could be because the stress of bullying compromises kids' immune systems. Or they may be faking an illness to escape an attack. Dr. Tom Tarshis, the medical director of the Bay Area Children's Association, explains that aggressive kids may have the same mental health problems that their victims do. "When you're a bully at elementary school you're more likely to be excluded from playground games. [Other kids] don't want to be friends with you," he said. The study suggests that nurses may be key in identifying which kids are experiencing trouble, since kids will often hide the bullying from their parents and teachers. However, Tarshis added, "We have to make sure the teachers are on board, the parents, the administrators, and the whole community."